1. Field of the Invention
The invention relates to a process for the synthesis of 2-furylketones.
2. Description of the Prior Art
Biological fouling, or biofouling, is defined as the unwanted buildup of microorganisms, plants, and animals on artificial surfaces. Marine biofouling is the undesirable accumulation of organisms on any artificial surface that is submerged in seawater, such as ship hulls, seaside piers, sea defenses, or any other surface that is continuously in contact with seawater. Fouling can occur in two basic forms, hard fouling, such as barnacles, and soft fouling, such as grasses and algae.
Current antifoulant technologies have been found to be both harmful to marine life and to the environment. Presently, the most commonly used antifouling agents in marine coatings worldwide are organotin compounds, specifically tri-butyltin oxide (TBTO).
While tri-butyltin agents have been very effective in preventing fouling they also are associated with a vast number of environmental problems, due to their persistence in the environment, such as bioaccumulation, acute toxicity, and reduced reproductive capability of marine organisms. Similar concerns exist for coatings that release copper into the environment.
Naturally occurring antifoulant compounds, those expressed by marine organisms, are only available in limited amounts and often their structural complexity makes synthetic production in large quantities difficult. One analog of a naturally occurring antimicrobial agent, 2-furyl-n-pentylketone, has been a popular synthetic target. Furan derivatives are known to possess marine antifouling properties as disclosed in U.S. Pat. No. 5,259,701 to Gerhart. The majority of past synthetic strategies have involved Friedel-Crafts acylation chemistry and often resulted in poor yields and were rarely applied to large-scale preparations and/or involved the use of complex, expensive reagents. Other oxidative strategies of an α-hydroxyl furan have proven difficult to carry out and the resulting ketone products often require chromatographic purification, which is troublesome for larger scale preparations. Various types of Friedel-Crafts acylation methods have been used to prepare. Most have employed furan and an acid chloride or anhydride with a range of acid catalysts. Other groups have prepared 2-furyl-n-pentylketone by way of a facilitated acylation reaction between boronic acids and anhydrides in the presence of a palladium catalyst. Alternative methods employed to prepare 2-furyl-n-pentylketone have involved an alkylation scheme usually involving either an acid chloride or furfural with the appropriate Grignard reagent. Alkylation in the case of furfural then required oxidation to afford the desired ketone product. Alternatively, 2-furyl-n-pentylketone may be prepared by way of the hydroacylation of 1-pentene with furfural in the presence of cocatalyst Wilkinson complex and 2-amino-3-picoline.